Saturday, April 30, 2011

Predators of the Touch Tank

            We had a casualty in the touch tank this morning.   Sometime between around 9pm last night, and 10am this morning, one of the starfish in the touch tank ran afoul of a crimson anemone.   The anemone wasn’t even one of the large ones; in fact, it’s only about half the size of the sea star in question.   To be fair, the sea star wasn’t doing all that well to begin with; one of the aquarists had moved it into the anemone pool from the sea star tank because the larger sea stars seemed to be picking on it.   Possibly if it had been in better shape to begin with, it would have been able to extricate itself.   The first think I knew about it was when I uncovered the tank in the morning – and two starfish arms were sticking out of the anemone’s mouth.   I radioed the aquarist (he was amused that I used the euphemistic phrase ‘health check’, for what was pretty obviously a half-eaten animal); we were both of the opinion that at this point, it was really too late to do anything but let the anemone finish his meal.   The sea star was, unfortunately, still alive; for the next three hours I got to watch its tube feet flailing around as it was sucked all the way into the anemone.   

            Welcome to the touch tank, red in tooth and claw.   Although it isn’t always obvious to our guests, many of the touch tank animals are actually predators – for all that they are only a few inches long.  Also, most of them were collected from the wild.   Before coming to the aquarium, presumably these animals were surviving as predators just fine.  In the touch tank, our anemones no longer have to kill and eat other animals to survive, because we feed them what they need.   But that doesn’t mean they stop being predators.   That’s what they are.   

            With some animals, we even showcase their predatory talents for the edification of our guests.    Go ahead, touch the crimson anemone.    

              Do you feel the tentacle sticking to you?   It’s a little like touching a piece of scotch tape.   Believe it or not, that stickiness is actually the anemone’s stinging cells at work.   That little guy is trying to kill you and eat you.   Because humans are comparatively gigantic, and have very thick, multi-layered skin, the anemone’s chemical armament is woefully inadequate.   All they can do is stick.

            Regardless of their failure rate, the crimson anemones keep trying.  They’ll still be sticky for each one of the few hundred aquarium visitors that are going to touch them tomorrow.   They’re predators, and that’s what they do.   

The crimson anemone digesting his meal...

            Currently, the carnivorous anemone is swelled up to about three times its normal size.   I am guessing he has eaten enough food to last him for the next six months or so.   It’s interesting, but if the anemone had gotten ahold of the sea star a few hours earlier, or pulled him in a little quicker, we might never have known what had happened.   Someone would probably have noticed that one of the anemones had tripled in size overnight – but it might have taken a day or two for anyone to notice that we hadn’t seen the green starfish in a couple of days…

            Speaking of which, we are also missing two hermit crabs.  One was confirmed eaten by an anemone; all we found was part of a claw.   (The anemones are pretty serious predators.)   No idea what happened to the other one.   It might have been picked off by an anemone, or possibly it was done in by one of the larger crabs.   Of course, it could also be that the missing crabs expired of natural causes, and their tank mates simply took advantage of the free meal.  The touch tank hermit crabs, while uncannily passive towards people poking their shell, can be very aggressive towards other animals.   They steal food from the anemones, they snip the tube feet off of the sea cucumbers, and pull the opalescent bits off of the opalescent nudibranch.   One crab who used to live in the tank would occasionally snip arms off of the sunflower sea stars when he was feeling hungry.   

            But the hermit crabs seem to reserve their crabbiest behaviors especially for other hermit crabs.  When crabs molt their exoskeleton, it takes a day or so for the crab’s new exoskeleton to harden up (ever heard of soft shell crab?).   Some crabs take advantage of this temporary disability to rend the newly-molted crabs limb from limb.     It’s a recurrent problem with raising crab.   When crab first hatch, they are very small (about the size of the period at the end of this sentence), and very numerous – so to feed the crabs, you have to find food that is even smaller and even more numerous to add to their water.   When they’re still in their larvae stage, it can be difficult to get the crabs to eat anything at all.   Then they get larger, and they start eating each other.   The attrition rate can be high.   

            Given how crabbily our hermit crabs behave, I am continually surprised by the number of kids that visit the touch tank who used to have one as a pet.  I dimly recall my parents buying me a hermit crab as a child, being by turns interested and terrified of it, and that it died a few months after we bought it.   This also seems to be the experience of most of the small children who visit the touch tank.   I have yet to meet any kid who’s managed to keep a pet hermit crab alive for any length of time.   I sometimes wonder if this isn’t some sort of deliberate parental plan – that the first death of a pet that their child experiences will be a pet that isn’t all that loveable in the first place.          

            Since it can be almost impossible to raise some of these animals to adulthood in the safety of an aquarium tank, I have a lot of respect for all those crab living out in the wild.   For most crabs, just growing to the size of a penny is a major accomplishment considering that thousands of their siblings did not make it that far.   Have you ever seen the Discovery Channel show Deadliest Catch?   Some of those crab fishermen will make their fortune by the number of king crabs they catch each winter.   They’re the lottery winners in an industry that is statistically more deadly than almost any other occupation there is.   Now, think about all of those big king crab getting pulled out of crab pots and stuffed into the hold.   They were lottery winners, too.   Right up to the moment they wandered into the crab pot.

King Crab

Tuesday, April 26, 2011

'An Excellent Place to Observe the Habits of Human Beings'

            Evan Esar once called zoos an excellent place to observe the habits of human beings.   This is certainly true for the touch tank - especially when there are lots of families visiting.   At times, the touch tank is almost like a tree stand from which to observe various parenting strategies at work.

            The parents that are most successful at getting their kids interested in touching the animals are the ones who are interested in the animals themselves – or at least are willing to feign an interest long enough to convince Junior that the anemones aren’t going to eat his finger.   (Some small children don’t even want to come near the tank one they realize that there isn’t a lid on it.)    

            Then there are the parents who are benignly tolerant of whatever their youngster wants to do – they’ll stand back and take pictures, and let the kids pet the sea urchins if they want to, but they’re also totally fine if all the kid wants to do is splash the water around, or peer through the glass at the hermit crabs.   (Look, Mom - he's moving his claw...)   Really young kids just get a kick out of putting their hands in the water.  It’s a lot of fun to watch their faces when they find out that our 39-degree tank isn’t exactly bathwater temperature.   One kid just wanted to swim his hand through the anemone pool and pretend to be a sea lion.

            These also the parents who seem to be on a continual quest to keep up with their easily distractible offspring.   The family could have spent only 30 seconds at the touch tank, but as soon as the kid sees something else interesting, he’s off like a shot, and the parents grab the stroller and take off after him.   When my mother took my sister and me to museums, she had a rule that we couldn’t leave an exhibit until we had actually read the accompanying panel – thereby preventing us from bouncing around the gallery like blonde-haired ping-pong balls.   In nearly four years of sporadic interpretation at three different zoos and aquariums, I have never seen another parent duplicate this trick.

            Then you have the parents who don’t make any attempt to keep up with their kid, or who view the touch tank as some kind of on-premises babysitting service.   Which is absolutely, totally fine with some kids – like the teenage girl whose mom spent twenty minutes in the aviary photographing the puffins – you could almost see her ‘Uncool Parent’ meter ticking into the red zone.   Significantly less fine are the three unsupervised kids who want to climb on the fiberglass sea lion, or use the eider spotting scope to look down each other’s throats.

            What I absolutely can’t stand are the parents who actually call their own kids sissies for not wanting to touch a starfish.   Yes, some people do this, and it depresses me every time I see it happen.   I mean, it’s a starfish.  It’s only a damn starfish.   If your kid just wants to look at it, let him bloody look at it.  Or, you can grab his wrist, force your kid’s hand underwater, poke the starfish a couple of times, and tell your kid, see, that wasn’t scary at all.   I should ask the exhibits guys to make me a sign - “This aquarium encourages the use of positive reinforcement in the training of our guests.   Any parent using the words scardey-cat, sissy, or wimp will be asked to sit and look at the octopus while their child enjoys the touch tank at his or her own pace.”

            A man was at the touch tank with his son, who looked to be about seven years old.   The dad was calling his boy every name in the book trying to get him to touch one of the starfish, and the kid was standing there looking miserable.   Some kids, especially the younger ones, feel like they are perfectly justified in not wanting to touch something gooey with more tentacles than they can count.   This boy wasn’t one of those – he was very obviously scared of it, and just as obviously mortified that he was scared of it.   His dad says, if you’re going to be a pussy then we’re done here, and walks off to the other end of the gallery.    The boy is still standing there, staring at this giant purple sea star.   And I think, that bastard has set this up so that failing to touch a starfish is failing his dad.   

            So I stick my hand in the tank and start petting the starfish, and tell this boy every single comforting fact about starfish that I have learned in three years of being the touch tank lady.   He’s very soft, and because he’s so soft, we have to be gentle when we touch him.   He moves really slowly.   His mouth is on his belly, and he doesn’t have any teeth.   His favorite food is mussels.   He won’t crawl out of the tank because being out of the water isn’t good for him.   The boy asked a question (good sign) and dipped a finger in the water.   He touched the starfish, very gently, and looked at me, as though it was important that someone knew that he’d been brave.   And he had been brave – and his father wasn’t around to see it.

Monday, April 18, 2011

Silt, or the Aquarium meets Jaws

When the barge arrived, the touch tank got very scary for a few hours over the weekend.

The aquarium is in the middle of a major project to clean out our saltwater intake lines – these are two big pipes that take salt water out of the bay and into the tanks in our building.   So yesterday, the big barge, which is going to be the staging area for an upcoming phase of the pipe project, arrived in Resurrection Bay, and anchored itself directly over the intake pipes.   Unfortunately, the anchoring process apparently churned up quite a bit of muck off of the bottom of the bay - which was immediately sucked up by the pipes and fed into our tanks.   So, for a good portion of Sunday morning, the exhibit tanks looked… well, a little scary.   The water was very grey, and cloudy, and every so often, a silhouette of a fish would flicker by, or a few strands of kelp would wave in the current.    It was actually very cool seeing Woody swimming around in the sea lion exhibit – he looked like a monster-sized shadow drifting across the window.   All we needed to do was glue a shark fin onto his back, and we would have had an entirely different exhibit…   

Since there weren’t visible animals in all of our tanks, we discounted admission for the day, and people seemed happy enough with that – at least no one complained.   And the mammal husbandry staff made a point of radioing every time they were doing a feeding session, so the guests could congregate and watch.   (Woody does handstands.   No guest who sees one will depart unimpressed.)   

Some of our tanks actually looked pretty atmospheric - especially around mid-afternoon, when the water began to clear enough that the fish were visible, but the back walls of the tanks themselves were still very shadowy.   In some ways, the silty look is probably a little closer to what the water in Res Bay actually looks like – so full of glacial silt and plankton that you can’t see a whole lot else.   On good days in Aialik Bay, you could see down about eight feet.   At the aquarium, you can (usually) see all the way to the bottom of our deepest tanks, around 20 feet down.   

The Kelp Forest tank looking mysterious

The seabirds in the aviary certainly noticed that there was something going on with their water; they kept sticking their heads underwater and looking around.   And when Eden and Tasu came out into the habitat later that afternoon, they seemed even less happy than usual about getting in the water with Woody, their 2000-pound would-be boyfriend.   I don’t think they liked the idea of being in the water with him, but not being able to see where he was.   Eden jumped in eventually, and she and Woody spent a few minutes nuzzling and nipping, which seems to have become their standard way of saying hello.   (If Woody gets too rough with her, she’ll turn around and bite him on the lip; Eden may be our smallest sea lion, but she knows how to take care of herself.)

The touch tank, however, was just downright scary.   For the first few hours we were open, the water in the tank had the consistency of chocolate milk – this solid grey expanse of water, broken occasionally by gelatinous anemone tentacles, or prickly urchin spines waving above the surface.   Not a very inviting sight for the touch tank.   It was impossible to see any of the animals at the bottom of the tank – and even I did not want to stick my hand all the way to the bottom of the tank, for fear I would get too close to a pissed-off hermit crab.   (I’ve never seen any of our crabs pinch anyone, ever – but I have seen them try a couple of times.) 

By the end of the day, the debris kicked up by the barge seemed to have settled back down, and the water in most of the tanks looked noticeably clearer.   However, many of the touch tank animals looked two or three shades greyer than they normally did, from all of the silt that had settled out on their backs.   The sea cucumbers looked particularly dingy; it almost looked like I needed to go through the tank with a feather duster.

I do want to mention that having silt in our water – even in quantities large enough to cloud up a six-inch tank – is in no way harmful to the animals that actually live in the water.   Silt is naturally found in the water in Resurrection Bay, (after major rainstorms, the Bay can become very silty just from increased surface runoff), and the critters that live in the Bay deal with the silt just fine.   (Also, any bits of plankton or food particles that were sucked into the pipes will be eaten with relish by the anemones, barnacles, and other assorted filter feeders living in the building.)   The silt is really only an annoyance to the guests - and to the aquarium staff whose job it is to clean this stuff out of our tanks.